Screw press



A. CLEMENTS March 31, 1942,

SCREW. PRES S .5 H M .2 N w a Yw w m J 3 llll'lu m w N w m Maz 'ch 31,1942. A. CLEIQENTS,

sheets-shet s SCREW PRESS Filed Nov. 22, 1940 jj odezozazs JEZZerZCZemzs Patented Mar. 31, 1942 UNITED sins- A ,,LPAT ENT oF-rrce SCREWPRESS Albert-Clements, Berwyn, 111., assignor to Verson Allsteel PressCompany; Chicago, Ill'.,, a corporation of. Delaware ApplicationNovember 22, 1940, SerialNo; 366;610-

6 Claims? My invention relates to a screw metal drawin and stampingpres's havin'g a stroke of variable length;

In general the i press I of wardly' and downwardlyi by means of a"rotating nut -threaded to a longtscrew secured tol the 't'op" In :theoperation of the press] the nutfis' first rotated in? one" direction: tomove the slide downwardly to the desired? point where uponthe' slidefora membenmovablel therewith actuates: a limit switc'hrwhichc causes thenut to" be" rotated in the oppo'site direction thus" retract ing itheslide.

When the slide'reachesthe upperlimit ofits stroke of predeterminedlength; a second'limit switch is actuated and the motionoff' the slideceases; By shifting the positions. of the' two limit switches thelowenan'dupper limits of the stroke of the" slide may be. predetermined sothat anoperatorwill mei'ely'i'ieedztoactuate asta'rt ing' control'inorder to"effect'-acycle of operation of" the p'ress,ithatis, after ametal blank has been placedv in position; the operator wil1:actuaterthestarting control: This-will cause-*theen ga'gem'ent" of a clutchand'th'e release'of a? brake thus causing the slide to "move downwardlyand again upwardly to it's starting position'.

This novel pressembodies mostofthe ad vantages inherent in hydraulicpresses andlike hydraulic presses is readily adaptable: to usesrequiring a longstro'ke at compara-tively'uniformz" speed. During thecourseof the! following: description, it- I will also become apparent"that the length of stroke of the press embodying the pres--- entinvention is'readily variable toacco-mmodate the pressto-a 'multitudeof-metal:drawing: and stamping-1 operations. In the present press anarrangement" isshown whereby the die-may be' retracted to its-uppermost-positionmore rapidly' than it -is moved= downwardly:during-its working" stroke; thus enabling the completion ofta' cycle ofoperation .in less time+that-would be required iftheslidewere moved'at'aconstant spee'd. i In" general;v therefore; it is an'objectof-the'present invention to provide at n'ovelmechanical pressembodying"the above desirable features:

Itis a'- more specific'ob'ject of the presentin vention' to providea'novel screw press having a" stroke of variable-length.

An additional object is to provide? a screw press havingmost oftheadvantagesrainherent'in hydraulicpresses:

Still another object is theprovision of ascrew" the'present inventionconsists of a reciprocating slide J to which a die member is attache'diThis'slide is: moved up press having most of the desirable "features" ofhydraulic presseswithout the'inh'erent limita tions of such'prsse's and"whichca-n be m'anu factured at comparatively low cost as" compared 3whydraulic presses of "similar capacity;

Still' another object'of the present -'nvention is to provideamechanical press having a stroke ofvariable'length and in" which the'return stroke of the slide is faster th'antheworkingstroke;

time of the cycle of operationoi the press" is progressively shorter asthe stroke is shortened." 153 in which Fig. 1 is a front elevation ofapress embody ing the present invention witha -portionof the' crownthereofbroken away to -show the operat- 24 ing mechanism therein;

Fig. 2 is a-side elevation of the press shown.

in .Eig. 1-as observed fromVthe-right;

Fig; 3 is aleft-hand side elevation .of the upper portion of the pressshown in Figsrl and- 2; and

36;; Fig.4 is a somewhat diagrammatic longitudinalvertical sectionalView through the clutch and. brake mechanism of thepress'and may beconsidered as taken in the direction of the varrows along the line 44 ofFig. 2.

35;, In the embodiment of my. invention illustrated in the drawings, Ihave shown a screw type press having a, stroke variable from zero to themaximum for which the particular press is designed. This press,indicated generally by the numeral 4%"), is comprised of a frame l2 anda slide l4. At the lower portion of the frame a bed I5 is adapted" tosupport a lower die element, not shown, while the lower surface of theslide M- carries' a cooperative die element, also notshown in thedrawings. At the upper'portion of the frame the press is provided with acrown lfiat' the top of'which a drivin'g'motor lBis mounted upon'brackets 20.

Thepulley22 of the motor 18 is connected by means of'amultiple V beltdrive 2A to a" heavy fi'y'wheel 2fi journaled" upon a horizontal"transve'rseaxis'in bearingmembersfiilz These bear-'- ing members are, inturn, fixed in brackets'i3fl" which extend: inwardly and are secured to'the rearward face of the crown Hi; A right ha'ndz Still another objectofmy inventionis'the provision of a novel-mechanical screw typepresshaving a stroke of variable 'length'w'herein'the-- Other objectsand'advantages'will becomearh parent from the followingdescriptionofla'praferred' embodimentof my invention taken inconjunction with the accompanying drawings in e which similar charactersof reference refer togolgsimila-r parts'throughout the" severalviews-and driving shaft 32 has its inner end piloted in a bearing member34 provided in the right-hand portion of the flywheel 26 in axialalignment with the outer bearing surface of the flywheel. Near itsoutward end, the shaft 32 is journaled to rotate in a bearing 36 carriedfrom the press crown upon a bracket 38 similar to the previouslymentioned brackets 30.

A similar shaft 40 is journaled in the lefthand portion of the flywheel2B in axial alignment with the right-hand shaft 32, while neai itsoutward end this shaft 40 is carried to rotate in a bearing member 42similar to the bearing member 38. With this arrangement the flywheel isfree to revolve relative to shafts 32 and 40 while these two shafts arefree to rotate relative to each other as well as to the flywheel. Duringoperation of the press the flywheel is driven at a substantiallyconstant speed by the motor I8 and thus is a source of kinetic energywhich, through mechanism to be described is adapted periodically to beconnected to the press slide to reciprocate this slide downwardly andagain upwardly to its retracted position.

At its right-hand side the flywheel 26 is keyed to a bell-like member 44of a clutch 46 which, in turn, carries an annular clutch driving disc48. This disc is free to move longitudinally slightly with respect tothe bell 44 but is secured against relative accurate movement by theexpedient of a splined coupling 50 between the bell and the disc.

Within the bell 44 a collar 52 keyed to the shaft 32 is provided with anannular clutch driven plate 54 which is positioned closely adjacent theface of the driving disc 48. A similar annular clutch driven plate 56 ispositioned on the opposite or outward side of the driving disc 48 and isfree to move longitudinally relative to the clutch plate 54 on splines58 formed around the circumference of the collar 52 but is preventedfrom rotating relative to the plate 54 by these splines.

An annular piston 60 operating in a cylinder 62 secured to the shaft 32acts to urge the driven clutch plate 56 toward the driven plate 54 whenthe cylinder 62 is placed under pneumatic pressure, thus clamping thefloating clutch driving disc 48 between clutch plates 54 and 56. Thiscylinder receives air under pressure through a port 64 whichcommunicates with an outwardly extending passage 66 in the shaft 32. Airis fed to or exhausted from this passage 88 through an air line 68 andcap 10. The cap fits over the outer end of the shaft 32 and is sealed tothe shaft by a cup washer I2 or other suitable rotary seal. Thus, byadmitting air under pressure to the air line 88, this air is caused toflow through the cap I0, passage 68. and thence through the port 64 intothe cylinder 62. The resulting increase in pressure in the cylinder 82moves the piston 60 toward the flywheel thus pushing the clutch plate 56against the disc 48. Continued movement of this piston urges the clutchdisc' disengaging the clutch when air is exhausted from the cylinder 62.

A similar clutch is arranged at the lefthand side of the flywheel andsimilarly connects the flywheel to the shaft 40 when engaged. Thisclutch is actuated by a piston 82 acting in a pneumatic cylinder 84 inthe same manner that piston 60 actuates the previously mentioned clutch48.

Directly to the left of the clutch cylinder 84 the shaft 40 is providedwith a collar 88. The external face of which is provided with splines88. A bell formed as a portion of the bracket that supports the bearingmember 42 extends inwardly and overhangs the shaft 40 and atapproximately the midpoint of the collar 86 is provided with an annularbrake disc 92. The connection between the brake disc'92 and the bell 90is splined at 94 to permit a limited longitudinal movement of the brakedisc while preventing relative rotation between these elements.

An annular brake plate 96 is slideably mounted upon the splines 88 andis secured to the outer ends of clutch release pins 98. These pinsextend through the cylinder 84 and are secured at their opposite ends tothe piston 82, while the portions of the pins between the cylinder 84and the brake plate 98 pass through coil springs I00, thus these springsI00 act in the same manner as the springs 14 to release the clutch whenair is exhausted from the space within the cylinder 84. In addition itwill be seen that since their outer ends are connected to the brakeplate 96, these springs will urge this brake plate against the brakedisc 92 simultaneously with the disengagement of clutch 80.

At the opposite side of the brake disc 82 the splined collar 86 isprovided with a similar slidable brake plate I02 which is connected bybrake release pins I04 to a brake release piston I06 slidable in acylinder I08, thus movement of the piston I08 toward the left pulls thebrake release pins I04 toward the left, thus pulling the brake plate I02away from the disc 92. Coil springs 'I I0 surround the pins I04 and bearwith their opposite ends against the plate I02 and the cylinder I08 sothat the brake plate I02 is normally pushed toward the right by thesesprings. The two cylinders 84 and I08 are connected by concentricpassages H2 and H4 in the shaft 40 to air lines H6 and 68, respectively,through the medium of a cap II8 having a pair of rotary seals I20 andI22 so that air may be admitted to or exhausted from either the cylinder84 or the cylinders I08 and 62 together.

When at rest, all of the cylinders will be at substantially atmosphericpressure, thus both of the clutches will be disengaged while the springsI00 and H0 act to urge the brake plates 96 and I02 from oppositedirections against the brake disc 92 thereby preventing rotation of theshaft 40. Simultaneously with the engagement of clutch 80 the brakeplate 96 will be drawn toward the right and the brake released. If, onthe other hand, cylinder 82 is placed under pressure to engage clutch48, the arrangement of the air lines is such that brake release cylinderI08 is simultaneously placed under pressure to move the brake plate I02to the left thereby releasing the brake to permit free rotation of thedriving mechanism.

Near its outer end, the shaft 32 is keyed to a pinion I24, While thecoaxial shaft 40 is also keyed to a similar pinion I26. These pinionstermediate gear I30. The diiference in the sizes of the two -drivin'ggea'rsisso arranged that thelarge gear I-32- is driven at a" somewhatslower speed than the large gear I34: Aswill appearmorefully'subse'quently, this is done so that the return stroke of the pressslide will be accomplished'in less time than the downward or workingstroke. I

A short shaft-I3'o is keyed t'o the large gear I32" andextends-inwardly-through the crownifit'oa position approximatelyone-third-of the distance across the crown while a similar shaft I38 iskeyed to the gear I34-=' and extends inwardly through the crown inaxial-alignment with the shaft I36.- The innerends'of' these shafts areprovided with bevel gears I4Il'and I42; respec-. tively, meshing withalarge ring gear I44 rotatable in a horizontal plane positioned atapproximately the center of the crown.

This ring gear I44 is keyed to' a-rotat'able nut I46, the upper face ofwhich is flat and bears against a bronze annular thrustp'late I48secured against the lower face of the crown. Anannular retaining'ringfill-surrounds the nut I46 and-isattached to the=lowerface of the crownby bolts- I52; This ring serves to hold the nut in place by meansof aflange I54at its outer-end which ex tends inwardly to embracea--shoulder formed upon the nut. The retaining'member IMF-thereforepermits the nut to be freely'rotatableb'ut prevents the axis of the nutfrom becoming displaced' and also prevents endwise movement of the nut.Directly above the nut a cylindrical opening I56 extends through the topof" the crown; This openingis of'somewhat greater di ameter than thethreaded opening throughthe nut'and provides'a passage foracomparatively longscrew I58 'threadedto the nutI46;

The lower end of thisscrew I58carries an annular flange I66 whichis'secured" to the upper face of the slide I4 by'means of a plurality ofcircumferentially spaced'cap screws I622; Thus the screw and slide aremoved together either upwardly or downwardly'by the nut I46, dependingupon thedirection' of rotation of the latter. The upper end of theopening I56 through the top of the-crown is closed by a cap I641 Thiscapisintended merely to close the opening I56 and provide a housing intowhich the upper end of'the screw I58 can extend when the slide I4 isretracted "to its uppermost position;

The control ofthe press I have shown is intended to be exercised byupper and lower limit switches I66 and I68; respectively, whichcooperate with a pin I'III secured'to the slide I4; that is, the limitswitches I66 and I66 are shifted to any desired position vertically uponthe press frame so that as the slide moves upwardly, the: upper switchI66 will be tripped by the pin I thus energizing a circuit to stop thepress, while similarly, downward movement of the slide trips the lowerlimit switch I63, thus momentarily stopping the press and subsequentlythereafter reversing its stroke to return the slide I4 to its retractedposition.

The use of limit switches to start and stop varcircuits; operatesolenoid air valves-which admit'.

air t'oor exhaust a'ir 'from th'e cond iiits' 68 i and I I 6 in themanner 'described b'elow.

The operation 5 of the pressof m-y-"invention lo -asfollowsz With theelectric motor I8 operating;

theflyw-heel 26 will be'r'otatecl at'a comparatively constant speed.Before the commencement-- of the cycle of operation, however, the twoclutches 46 and 8llwill be-disengaged and the'brak eisho'es 96 an'd I 02will be clamped against the brake'disc 92rby'the coil springs I00 and'III]; This'is the condition assumed by the machineiwheni the air: linesI I6 and BB areat substantially atmospheric pressure.

After a blank to be forme'd ha's beenpla'ced over the lower diemember,.air under'pressure is: admitted to conduit68. Thisair is communicated through passage 66' to clutch-'cylinder62" thus engaging clutch 46whilesimultaneously air :;under pressureis-oommunicated by conduit M4 tobrake release'cylinder I08 thusdrawing brake plate I62 to-the left.- Theflywheel therefore ro-'- tatesthe shaft 32 and through the medium of thegear train com-prisedof the pinion -I24, inter-' 3 ji'mecliate gear I28,and. large gear'l32, rotates the shaft I36-at a -reduceolrate of speed.The'bevel gear I46 carried by this shaft, inturn', rotates the ring.gear I44 ata reduced" speed and this ring: gear; in turn, revolves th'enut I46; thus causing-'- gg'the-scr'ew I5'8-and slide l4 tomovedownwardly to' produce-a Working stroke; Whenthe slide has substantiallyreached its desired" lower limit} the lower. limit switch I68 isactuated. Thisiswitch", through the medium of its electric circuit -andsolenoid valves 1 causes :air "to be exhausted from the'oonduit' 68;thus permitting springs'l'lto disengageclutchs lli': and simultaneouslyto permit,

springs I96 to apply-pressure against the brake plate 92. The press,therefore, c'omes'to" rest. Almost simultaneously. therewith air isadmitted under pressure-:toconduitiH63 This air isicom municatedthroughconduit I I 2 with a'ir cylinder 84 thuscausingpistom 82'to' bemoved to'=the* right to engage clutch 8llrand simultaneously to'wiretract the. brake plate-66.- The release ofthe brake'together withthe engagementof clutch 86' causes shaft 40' to 'rota-te with' theflywheel 26 and through the medium of ther'pinionx I 26, interme diate gearI36, and large gear I'34';-to'rotate1the sshaft' I38: The. rotation. ofthisashaft is communicated by means of bevel gear I42-'an'd ring gearI44" to the nut I46. Thenuti therefore; is revolved in the oppositedirection to that previously mentioned and causes the screw I58'-andcslide I4 to be moved'upwardly. s

As thepress' approaches the upper" limit of its stroke, .limitswitch I66is tripped and through the'-medium"of"itssolenoid" air valve causes airto be exhausted: from: the "conduit H6 with the .result that clutch 80is disengaged and brake plate 961s forcedfby springs Iflllagainstthe-brake disc 92. The press; therefore,- comes to rest and isincondition for a succeeding cycle of operation.

It' willbe seen, therefore, thatmerely by ad- -justing the positionsof'its limit switches I 66 and' I68, the upperlimitand'thelower-limit-of the stroke-of the press canb'e'determined'.

Having described my inve'ntion, what-"I 'claim as new and useful anddesire to secure by Letters Patent of the United States is:

1. For use in a metal deforming machine of the type in which a slide isreciprocable in a frame and in which the slide carries a screw threadedthrough a nut rotatable in the frame so that rotation of the nut in onedirection causes downward movement of the slide while rotation of thenut in the opposite direction causes upward movement of the slide: meansfor moving said slide through a complete and variable stroke by means ofa motor having insufficient capacity to deform the metal being workedcomprising, a motor, a heavy flywheel, means to drive said flywheel fromsaid motor to store kinetic energy in said flywheel, a pair of clutchesdriven by said flywheel, a gear train connecting said flywheel to saidnut when one of said clutches is engaged, a reversing gear trainconnecting the flywheel to said nut when the other of said clutches isengaged, brake means to prevent the rotation of either of said geartrains, and control means to effect the operation of said brake meansand said clutch means in a desired sequence, said control means beingadjustable to determine the length of stroke of said slide, wherebycontinuous operation of said motor will build up kinetic energy in saidflywheel, and whereby said kinetic energy can be used to revolve saidnut in either direction during predetermined intervals to effect upwardor downward movement of said slide to a greater or lesser extent.

2. For use with a metal deforming machine having, a frame, a slidereciprocable in the frame, a nut journaled to rotate in the frame, agear train to rotate said nut in one direction, a second gear train torotate said nut in the opposite direction, a screw attached to saidslide and threaded through said nut: a heavy rotatable flywheel, meansto drive said flywheel, abrake to prevent rotation of said nut, a pairof selectively operable clutch means to connect said flywheel to eitherof said gear trains, and means acting substantially simultaneously withthe engagement of either of said clutch means to release said brake.

3. For use with a metal deforming machine having a frame, a slidereciprocable in the frame, screw and nut means acting between said slideand said frame to move said slide when one of the elements of the screwand nut means is rotated relative to the other, a gear train to causesaid relative rotation in one direction, a second gear train to causesaid relative rotation in the opposite direction: a rotatable heavyflywheel, means to store suflicient kinetic energy in said flywheel tomove said slide through a metal deforming stroke and selectivelyoperable clutch means to connect said flywheel to either of said geartrains.

4. For use with a metal deforming machine having, a frame, a slidereciprocable in the frame, a nut journaled to rotate in the frame, agear train to rotate said nut in one direction, a second gear train torotate said nut in the opposite direction, a screw attached to saidslide and threaded through said nut: a rotatable heavy flywheel, a pairof clutch means selectively operable to connect said flywheel to eitherof said gear trains, brake means acting between said frame and one ofsaid gear trains adapted when engaged to prevent rotation of said nutand both of said gear trains, resilient means adapted normally to engagesaid brake means, and pneumatic means to overcome said resilient meansand release said brake whenever either of said clutches is engaged.

5. For use with a variable stroke mechanical punch press having a pressframe, a slide reciprocable in the frame, a rotatable screw and nutmeans acting between said slide and said frame to reciprocate saidslide, a heavy flywheel, means to rotate said flywheel in one directionto store kinetic energy therein, means including a clutch selectivelyoperable to rotate said rotatable means in one direction from saidflywheel, means including another clutch selectively operable to drivesaid rotatable means from said flywheel in the opposite direction, abrake to prevent rotation of said rotatable means when engaged, means torelease said brake substantially simultaneously with the engagement ofeither of said clutches and to apply said brake whenever both of saidclutches are disengaged, adjustable limit switch means adapted to betripped by upward movement of said slide to a predetermined point, saidlimit switch means when tripped adapted to release said clutches andapply said brake, and other adjustable limit switch means adapted to betripped by downward movement of said slide to a predetermined point, thelast said limit switch means adapted when tripped to release one of saidclutches and to engage the other of said clutches.

6. For use with a metal deforming machine having a frame, a slidereciprocable in the frame, screw and nut means acting between said slideand said frame to move said slide when one of the elements of the screwand nut means is rotated relative to the other; a gear train to causesaid relative rotation in one direction, a second gear train to causesaid relative rotation in the opposite direction, a rotatable heavyflywheel, means to store suflicient kinetic energy in said flywheel tomove said slide through a metal deforming stroke, a pair of clutchdriving elements mounted to rotate with said flywheel, a pair of clutchdriven elements adapted selectively to be connected to said clutchdriving elements, a shaft connected to one of said gear trains and toone of said clutch driven elements and piloted in one side of saidflywheel, a second shaft connected to the other of said gear trains andto the other of said clutch driven elements and piloted in the otherside of-said flywheel, brake means adapted when applied to preventrotation of one of said shafts, power operated means to engage one ofsaid clutches, power operated .means to engage the other of saidclutches and to'disengage said brake simultaneously with the engagementof the last said clutch, supplemental power operated brake means toengage saidbrake when the first said clutch is disengaged, control meansadapted when actuated to engage one of said clutches and to disengagesaid brake to permit the kinetic energy in said flywheel to causedownward movement of said slide, automatic control means adapted whenactuated to cause disengagement of the engaged clutch and engagement ofthe disengaged clutch so that kinetic energy in said flywheel will causeupward movement of said slide, and control means to limit the upwardmovement of said slide and to condition the mechanism for a succeedingstroke by causing disengagement of the engaged clutch and application ofsaid brake.

ALBERT CLEMENTS.

